Last year, Chavez had surgery to remove a cancerous tumor and has undergone further surgery and radiation in Cuba since. He returned to the island nation this month to undergo another surgery after publicly revealing that his cancer had returned.

He underwent a six-hour surgical procedure on December 11 that Maduro, in a televised address, declared a success.

A week after the president's surgery, the Venezuelan information minster said Chavez was battling a respiratory infection. Minister Ernesto Villegas said then that the infection was under control.

Recently both Villegas and Maduro have struck a somber tone when discussing the president's illness in contrast to previous government messages about his health. Villegas has suggested Chavez might not be not be back in Venezuela in time for his inauguration scheduled for next month.

Chavez addressed the delicate nature of his health before leaving Venezuela for Cuba. He said that if his health were to worsen, Maduro should replace him as president, making it the first time Chavez had spoken about a possible successor.